That’s the rough rule of thumb I can use for getting around town on my bike. Not bad eh? Compares rather well with the other modes of transport for getting in and out of London! That’s a proper door-to-door time as well so it accounts for waiting in traffic and at red lights (yes believe it or not the majority of cyclists do obey them….). My 10 mile commute this morning was completed in just shy of 40 minutes.
There have been occasions where this is a bit skewed, I had a horrendous time getting along Chelsea Embankment once due to sheet volume of traffic and when the last Harry Potter movie came out my progress down Hampstead Road, Gower Street and on towards Trafalgar Square was more a case of filtering practise then fast riding.
I think the only thing that has done a more consistent job of slowing me up is the snow in which case my journey times approximately double, which is still about twice as fast as motorised transport…..
So at 4 minutes per mile that gives me an average journey speed of 15mph, which is about right as my moving average is usually high 16’s/low 17’s so the small loss is expected once I account for time spent sitting still. Compare this to a car in London which apparently only averages 7mph according to some research carried out by Citroen.
So anyone who wants to complain about bikes holding them up should maybe have a look around next time they are sitting in a traffic jam. See all those things sitting around you and not moving? Yeah……..that’s what’s holding you up, not the cyclists who is disappearing off down the road.
Riding a century 
I only wish i was getting 4min miles, usually average just over 14mph on my commute but i have got a route with far too many traffic lights.
I actually miscalculated a tiny bit, it’s probably closer to 4 1/2 mins 🙂 I may have been lucky with the lights this morning and did do a +17mph moving average.